1. Field of the Invention
The present invention relates to a molding compound, and more particularly to a molding compound comprising resin and fibrous materials.
2. Description of the Prior Art
It is the conventional practice to mix phenol resin as a molding material with chopped strands of such fibrous materials as glass fibers, carbon fibers, aramid fibers or the like, cut to a length of 1.5 to 6 mm, thereby improving the strength of molded articles.
Molded articles can be produced by injection molding, transfer molding or the like, for example, by melting a compound and passing the molten compound through a mold cavity. When there is an obstacle such as a pin, an insert or the like in the mold cavity, or when the molding is carried out by multigating, the molten resin behaves in such manner that one flowing molten resin stream is separated into a plurality of substreams at the forward end of the stream once and then joined together, and thus occurrence of weld lines is inevitable.
The strength along the weld lines formed by molding the conventional compound, particularly the strength against the tensile stress in the direction perpendicular to the weld lines is very low. Phenol resin compounds containing chopped strands are not exceptional.
Since the polyphenylenesulfide resin has good heat resistance, chemical resistance, dimensional stability, electrical insulation, etc., it is used in many fields including electrical or electronic fields and automobile field. However, in molding of the resin into products of complicated shapes by injection molding, transfer molding or the like, generation of weld lines is inevitable as in the case of phenol resin, and thus an improvement of the strength against the weld lines has been so far desired.